Some properties of α-amylase in the digestive system and head glands of Cryptolaemus montrouzieri (Coleoptera: Coccinellidae)

Ahmadi, Fatemeh; Ghadamyari, Mohammad; Khani, Abbas; Ghadamyari, Mohammad

doi:10.48311/jcp.2012.1036

Some properties of α-amylase in the digestive system and head glands of Cryptolaemus montrouzieri (Coleoptera: Coccinellidae)

Authors

Fatemeh Ahmadi ¹

Mohammad Ghadamyari ²

Abbas Khani ³

Mohammad Ghadamyari ²

¹ Department of Plant Protection, Faculty of Agriculture, University of Zabol, Zabol, Iran.

² Department of Plant Protection, Faculty of Agricultural Science, University of Guilan, Rasht, Iran.

³ Department of Plant Protection, Faculty of Agriculture, University of Zabol, Zabol, Iran. Tel. and Fax: +98-542-2242501; E-mail address: abbkhani@yahoo.com

10.48311/jcp.2012.1036

Abstract

Biochemical characteristics of α-amylase in the digestive system and head glands of Cryptolaemus montrouzieri, a key predator of citrus mealybug, Planococcus citri (Pseudococcidae), were studied. The major isoform of α-amylase with the same molecular weight was detected in both gut and head glands loaded on polyacrylamide-starch gel electrophoresis. Moreover, a minor band with much lower intensity was observed in zymogram analysis of gut. Results showed that the specific activity of α-amylase from head glands (0.89 ± 0.02 μmol/min/mg protein) was significantly more than that of digestive system (0.76 ± 0.01 μmol/min/mg protein) in common condition (temperature equal to 25 ± 1 ^oC). The optimal pH and temperature for α-amylases activity were determined to be nearly 4 and 50°C in digestive system and 6 and 60 °C in head glands, respectively. EDTA (Ethylenediamine tetra acetic acid), Mg²⁺, Na⁺, Co²⁺, Fe²⁺ and Ca²⁺ inhibited the enzyme activity but Ba²⁺, Zn²⁺, Hg⁺ and K⁺ enhanced enzyme activity in digestive system. EDTA and all tested metal ions except Ba²⁺ inhibited the enzyme activity of head glands. Detectable levels of α-amylase activity in the insect reflect adaptation of the coccinellid for using starch granules or sugars (honeydew; sugary excreta of homopterans; and nectar) as a source of food in addition to predatory habits.

Keywords

&alpha

-amylase

digestive enzyme

Cryptolaemus montrouzieri